The present invention involves and discloses several modifications/versions of systems (and related methods) that transduce, or convert, power in a moving fluid (i.e., kinetic, fluid-flow power, such as wind power and water power) to electrical power, or vice versa.
A major field of use for the special features of, and contributions made by, this invention is that field which involves the conversion of wind power to electrical power. Accordingly, and while recognizing that there are several fields particularly suited for use of the present invention, we make a principal description of the invention hereinbelow in the field of wind-to-electrical-power activity. We also discuss briefly below the somewhat broader notion of the conversion of fluid-flow power to electrical power. Thus, a preferred way (and certain variations thereof) for implementing and practicing the system and methodology of this invention is(are) disclosed specifically in relation to wind-turbine, electrical-power generationxe2x80x94a realm of enthusiastic, xe2x80x9calternative-powerxe2x80x9d activity, wherein the various unique characteristics of the invention have been found to offer particular utility.
Typically, aerodynamic, wind-driven, rotor-operated, electrical generator systems collect and convert variable-speed wind power to electrical power by gathering fluid-motion energy, via an aerodynamic rotor which is positioned in a selected wind path, and by coupling the fluid-flow energy which is extracted and collected by that rotor (and its rotation) to the rotor in an electrical generator. Normally, the resulting electrical power output (typically AC) created by such a system, wherein the aerodynamic rotor is usually a propeller-type (also referred to as a fan-blade-type) rotor, is coupled, ultimately, to a conventional, commercial electrical utility grid which, possessing certain well-known constraints, requires that electrical power delivered to and handled by it have a certain, fairly rigorously maintained xe2x80x9celectrical qualityxe2x80x9d. Specifically, such a grid normally imposes a xe2x80x9cqualityxe2x80x9d constraint which requires that xe2x80x9creceivedxe2x80x9d power be delivered and maintained, at or very close to, a prescribed AC voltage, and as well, at a prescribed, and quite rigidly anchored, operating frequency (60-Hz is normal).
Accordingly, and to achieve successfully such required xe2x80x9cgrid constraintsxe2x80x9d, prior art systems typically include a certain, necessary level of structural complexityxe2x80x94complexity which is xe2x80x9coperationally disposedxe2x80x9d intermediate the contributing aerodynamic rotor and the grid. High on the list of culprits to be dealt with in a system of this type is the fact that power derived from the usual flow of wind is unpredictable, and highly erratic, and also widely variable, because of wind-speed variations. If left unaddressed, such power would not be acceptably deliverable to such a grid.
Thus, and traditionally in many prior art renditions of such a system, there is not a direct-drive condition existing between the wind-driven rotor and the rotor in an electrical generator. Rather, normally interposed (as a connective xe2x80x9cchainxe2x80x9d) the usual, fan-like, aerodynamic rotor and the grid is a speed-increaser gear-box, or the like, which has its input side coupled to the aerodynamic rotor, and its output side coupled to the rotor in a conventional electrical generator (any type). This gear-box serves to make the output operating electrical frequency of the generator relatively close to the grid operating frequency. Additionally, there is usually also often employed an appropriate category of electrical control interface circuit which couples, and which is interposed, the output of the generator and the input structure of the grid. This circuit interface cooperates in helping to furish the grid with the proper electrical-power quality.
Another type of prior art system recognizes that, in certain instances, there are advantages and efficiencies to be gained where there is a direct-drive connection in existence between the usual fan-like aerodynamic rotor and the rotor in an electrical generator. Here too, it is usually normal that the output of such a generator is coupled to a grid via an electrical control interface circuit of the type just mentioned generally above.
In each of these two conventional kinds of systems, the usual derivation of power by a propeller-type aerodynamic rotor, and the delivery of such propeller-derived power via a relatively small-diameter shaft which is connected to such a rotor, introduce inefficiencies and resulting power losses which one would like to overcome. While there are many sources of such inefficiencies and losses, prominent on the list of contributors are shaft-bearing losses, and gear-box loss.
In this prior-art setting, the present invention provides a novel, significantly improved, direct-drive-type, power-conversion (transduction) system, and a related methodology, which offer a number of significant improvements over prior art systems. These important improvements reside typically, inter alia, in the areas of (1) operational efficiency, (2) simplicity of manufacturing, and (3) reduction of system vulnerabilities due to the normal (and occasionally extreme) fluctuations in fluid (wind) velocity.
In the arena of converting fluid-flow power to electrical power, the invention has important applicability especially in relation (a) to fan-like aerodynamic rotors, (b) to hoop-shaped, or squirrel-cage-like (rotary-spool-like), aerodynamic rotors (and rotor sections), and (c) to various hybrids of (a) and (b) which have both squirrel-cage-like and fan-like characteristics. These three general kinds of rotors are also referred to herein, in order to convey a fuller understanding of the technical reach of this invention, as fluid-flow-dynamic, fluid-foil structures. The term xe2x80x9csquirrel-cagexe2x80x9d is a term with widely known familiarity in the art. These xe2x80x9crotorsxe2x80x9d are referred to hereinalso, variously, as fluid-responsive assemblies, as fluid-foil substructures, as air-foil assemblies (and spools), as fluid-dynamic rotors and foil assemblies, as wind-responsive portions of revolution structures, as wind-power-responsive units, and as wind-responsive instrumentalities. More about such rotors will follow in the discussion below. As one will observe from a reading of the discussion below, even various conventional rotors can be employed.
Importantly, the invention also has what might be thought of as reverse-performance applicationsxe2x80x94such applications relating to systems and methods that convert electrical power to fluid-flow power, as, for example, is done with fans, pumps, air-thrust engines, etc.
Accordingly, and referring back to certain earlier discussions herein, there are known in the prior art various power-conversion systems that, for example, transform power which is resident in a flowing fluid (the kinetic-power side of such a system) to (or from, when the reverse-conversion direction is thought about) electrical power (the electrical-power side of such a system). Examples of such systemsxe2x80x94i.e., wind-based systemsxe2x80x94have been discussed generally above. Analogous systems, of course, are known involving other types of fluids, such as water.
As is somewhat suggested by the discussion areas mentioned above, everpresent goalsxe2x80x94goals that are aimed at designing improved, fluid-flow, power-conversion systemsxe2x80x94include, inter alia, (1) increasing efficiency, in terms of power yield, (2) achieving maximum design and construction simplicity, and (3) holding system materials, building activities, and installation and maintenance, costs to a minimum. For power-conversion systems that must work well with the derivation of electrical power from a variable fluid-flow velocity, such as is usually present with wind, another critical design objective, certainly, is to develop, and to achieve (commercially successfully), mechanisms that accommodate (by xe2x80x9cevenizingxe2x80x9d) drastic, as well as ever-present-minor, changes in such velocity. How the present invention addresses these matters will become apparent shortly.
Further discussing and elaborating wind-turbine systems which have been in use for many years, limitations in the design and performance of these systems have prevented them from being used more widely than they have been. FIG. 1 provides a schematic illustration of a typical wind-turbine-type, power-conversion system 20. In this system, an aerodynamic, typically fan-type, rotor 22 (illustrated as a simple rectangle in FIG. 1) is connected, via a bearing-supported, rotating shaft 24, to the input side of a speed-increaser gear-box 26. Rotor 22 typically operates at a rotational speed in the range of about 20- to about 300-rpm. Gear-box 26 translates the rotational speed of shaft 24 into a relatively higher rotational speed in an xe2x80x9coutputxe2x80x9d shaft 28, which, in turn, is connected to the rotor in a conventional, electrical generator 30. A power-electronic, interface-control circuit 32 is sometimes (suggested by the dashed lines) used to control the generator (for example, rotor speed and shaft torque), and also to convert the generator""s variable-voltage, variable-frequency power to a standard utility voltage and frequency (the previously mentioned grid constraints). A conventional utility grid 34 receives output power from the generator and the interface-control circuit.
Rotor 22, as has been mentioned, is usually a propeller-type rotor, such as rotor 40 seen in FIGS. 2 and 3. In this rotor, plural blades 42 drivingly connect with, and extend radially outwardly from, a central hub 44. Hub 44 is connected to one end of a relatively-small-diameter shaft 46, which is supported by bearings, such as bearings 48, and which rotates with hub 44, and blades 42, in response to naturally incident wind W impinging on the blades. FIG. 3 shows a front view of rotor 40, which rotor optimally receives wind from a direction normal to, and into the plane of, this figure.
Other types of aerodynamic rotors have been used somewhat in the past. For example, another type of such a rotor is a generally cylindrical xe2x80x9csquirrel-cagexe2x80x9d or xe2x80x9choop-typexe2x80x9d rotor, such as the ones disclosed in U.S. Pat. Nos. 4,781,523, 5,425,619, 5,632,599 and 5,743,712 each of which patents is incorporated by reference into this document. Squirrel-cage rotors, which have not heretofore been directly linked to a direct-drive-type electrical generator, typically employ a hoop-shaped ring structure (a hoop member) which rotates around a horizontal central axis that is generally parallel to the direction of wind travel (usually nominally, generally parallel to the underlying xe2x80x9cground planexe2x80x9d). Such ring structure typically has peripherally, circumferentially and generally cylindrically arranged elongate air foils that direct air flow from the interior of the overall ring structure radially outwardly to the exterior, thereby causing the whole structure to rotate around the central axis. The mentioned air foils are typically disposed with their long axes substantially paralleling the central rotational axis. Squirrel-cage rotors often require what is referred to as a back panel structure which functions to direct oncoming wind through the usual, and necessary, air-flow spaces provided between the included circumferential air foils. A potential problem with such xe2x80x9cback-panelxe2x80x9d squirrel-cage rotors becomes very evident under circumstances where wind velocity spikes to a level that xe2x80x9coverpowersxe2x80x9d (i.e., laterally overloads) the back panel and/or the underlying ground-support structurexe2x80x94an event which can result in a catastrophic and destructive failure of the squirrel-cage system (rotor structure, support structure, etc.)
Another xe2x80x9cready-for-improvementxe2x80x9d issue involving various conventional power-conversion systems of the type now generally being discussed involves, in effect, xe2x80x9cmatchingxe2x80x9d the wind-flow-determined, operating, rotational speed of an aerodynamic rotor appropriately with the most appropriate rotational speed of the rotor in an electrical generator. Normally, such matching requires that a mechanical xe2x80x9cspeed-increaserxe2x80x9d be employed intermediate the aerodynamic rotor and the generator rotor.
There are two common types of speed-increasers that are used typically in wind turbinesxe2x80x94a gear-box, and a belt-and-pulley, transmission. Reinforcing a bit what was just above said about speed matching, a speed-increaser is required because of a mismatch between the optimally-efficient operating speed of the aerodynamic rotor and that of the electrical generator. The most efficient conversion (i.e. wind-flow-to-rotation) speeds of most aerodynamic rotors are much lower than the optimally-efficient rotational speeds of standard industrial electrical machines, such as squirrel-cage induction or synchronous generators (four-pole or six-pole). These machines are designed for relatively high-speed, low-torque operation. For example, the standard four-pole induction or synchronous machine generates at 60-Hz electrical power at a nominal rotor rotational speed of 1800-rpm. In contrast, and depending on the performance power level and size of the aerodynamic rotor operating in air, the aerodynamic rotor may have a typical operating speed in the range of about 20- to about 300-rpm. Depending on the wind-speed regime, the 20-rpm speed may apply to aerodynamic rotors designed to deliver about 600-kW to about 1500-kW of mechanical, rotating-shaft power. Similarly, the 300-rpm speed might apply to much smaller rotors designed to deliver about 2-kW to about 10-kW of rotating-shaft. Use of a speed-increaser significantly increases: (a) the number of required parts in a system; (b) the cost of manufacturing; (c) the design complexity; (d) the expected requirements and related costs for routine maintenance; and (e) the potential for mechanical failure. Use of a speed-increaser also results in a reduction of power-conversion efficiency.
Wind turbines that employ propeller-type rotors have been manufactured which do not require speed-increasers to translate shaft rotational speed between an aerodynamic rotor and a generator. Such systems are referred to as xe2x80x9cdirect-drivexe2x80x9d wind turbines. For example, and as is shown in FIG. 4, another conventional, prior art power-conversion version system 70 employs a propeller-type aerodynamic rotor 72. Rotor 72 is connected, via a rotary shaft 74, to the rotor in a direct-drive generator 76. Shaft 74 rotates with rotor 72. Shaft 74 is supported by suitably located bearings (not shown). Power-conversion system 70 is classifiable, generally, as a variable-speed configuration, which configuration employs appropriate, conventional power-electronic, interface-control circuitry 78 to control xe2x80x9celectrical operationxe2x80x9d of the generator (as well as other things such as the speed and torque matters mentioned earlier), and as a part of that control, to convert the generator""s variable-voltage, variable-frequency power to a standard utility grid-quality voltage and frequency.
One significant problem with prior wind-turbine systems, such as system 70 in FIG. 4, is that all rotational energy from the usual fan-like, aerodynamic rotor is transferred ultimately to the associated generator rotor through a shaft, like shaft 74. Thus, and as a natural result of this kind of xe2x80x9cpower-transferxe2x80x9d construction, such a shaft is subjected to fluctuating bending moments that increase fatigue and the probability of mechanical failure. Also, cyclic loading and unloading of such a shaft drains, and thus creates undeliverable, output power.
Thus, an important object of the present invention is to provide a unique, simple, easily manufacturable and efficiently operable, power-conversion system (and related methodology) for interconverting (potentially bidirectionally) moving-fluid-power and electrical power. The system of this invention is also referred to herein as a wind-power-deriving, electrical power generator system, and additionally, as an apparatus for converting kinetic, fluid-flow power to electrical power.
As will be more fully developed below, several structural, wind-power-to-electrical-power embodiments of the invention are proposed, illustrated and discussed herein. Each of these embodiments features a direct-drive system, and a related methodology, which are based upon the presence of a direct-drive coupling between an aerodynamic, fluid-power-acquisition rotor and the electromagnetic-generator rotor in an electrical generator. Such a generator rotor is also called herein a mechanical-rotation-responsive instrumentality. The required, associated generator stator is also referred to as a rotary-magnetic-energy-responsive instrumentality. Collectively, these two components (generator rotor and stator) are referred to as an electrical-power-generating assembly, as an electromagnetic (or electrical) generator assembly, and as a direct-drive generator (or generator section). In certain specific embodiments of the present invention, the electrical generator employed has a generally cylindrical configuration, with either the rotor or the stator functionally nested within the other one of these two components. In other embodiments, the generator has a generally pancake-like configuration, with the rotor and the stator functionally facing one another in the manner of two axially-stacked, relatively thin circular disks.
Each embodiment of the system of this invention also features an electronic interface circuit (or power-electronic control structure). This interface circuit (which could be either AC or DC in xe2x80x9cnaturexe2x80x9d) includes input and output sides connected, respectively, to the generator and to the final system-electrical-power-output which can be connected to a conventional, commercial power grid.
The most preferred embodiment employs a hoop-like aerodynamic rotor coupled, without the presence of any intervening rotary shaft, directly to the rotor in an electrical generator. The aerodynamic rotor and the electrical generator rotor are also spoken of herein collectively as a unitary revolution structure, and as a barrel-shaped, power-conversion device.
Another embodiment utilizes a fan-type aerodynamic rotor, also coupled, without there being any intervening rotary shaft, directly to such a generator rotor.
A third embodiment does employ a rotary power-transmission shaft, with a hoop-like aerodynamic rotor coupled directly through this shaft to the rotor in an electrical generator.
Still other embodiments have hybrid fan-like and hoop-like qualities.
Each such specifically shown and discussed embodiment of the present invention offers advantages, like those mentioned generally above, over known prior art systems. The embodiment which appears to offer the fullest level of advantage, and the one which is, accordingly, referred to herein as the most preferred embodiment, is a xe2x80x9choop-rotorxe2x80x9d, xe2x80x9crotary shaftlessxe2x80x9d embodiment.
Accordingly, one specific object of the present invention, thinking of the same in one, unidirectional, power-conversion sense, is to provide a novel system which functions to convert fluctuating wind power efficiently into electrical powerxe2x80x94especially, into grid-quality (or other regulated and controlled) electrical power.
Another object of the invention is to provide a wind-turbine system which does not require a speed-increaser to couple torque and power from an aerodynamic rotor to an electrical machinexe2x80x94i.e., a direct-drive kind of system.
A further object, one which is related to that just stated immediately above, is to provide a system of the type generally described, wherein fluid-power is extracted and acquired by the system in what, according to one preferred embodiment, can be visualized as an axially elongate, annular, hollow-cylindrical zone, or region, of space and manner, and then is conveyed, by way of mechanical rotation, also in an annular, hollow-cylindrical space/manner, and via what is referred to herein as a hollow, annular, cylindrical zone of rotating magnetic power, directly to a rotor in an electrical generator. Most preferably, perimetral, rim-to-rim coupling between (a) the perimetral rim structure in the aerodynamic portion of the rotating structure (which collects wind-power), and (b) the perimetral rim structure in the portion of the rotating structure (which works in conjunction with an electrical generator stator), effectively transfers all rotating power between these two rim structures without the presence of any intervening, small-diameter rotating shaft which, in accordance with prior art structures, becomes loaded with substantial cyclical, fatiguing, power-compromising torque. As has been mentioned earlier, a preferred system construction which employs this xe2x80x9crim-to-rimxe2x80x9d approach utilizes a hoop-, or squirrel-cage-like, aerodynamic rotor coupled directly to the rotor in an electrical generator. The aerodynamic rotor has a perimetral air-foil structure including aerodynamic vanes, or air foils (surface structure), which are spaced circumferentially to accommodate the radial passage of wind. The preferred unitary aerodynamic rotor and the generator rotor are referred to as being elongate, and as having a common, long, rotational (coincident) axis.
By way of an important ancillary comment at this point, and while keeping this particular, xe2x80x9cpreferred-embodimentxe2x80x9d approach specifically in mind (vis-a-vis the reference made to cylindricality), it is important to recognize, and to register the fact, that the present invention places a somewhat broader uniqueness-footprint in the sands of innovation. More specifically, if one simply substitutes (in a thinking sense) the termxe2x80x94surface-of-revolutionxe2x80x94(and the like) for the term xe2x80x9ccylindricalxe2x80x9d (used immediately above, and elsewhere herein) in reference to the acts of power-acquisition, power-conveyance and power-transfer, one will appreciate the general measure of this xe2x80x9cfootprintxe2x80x9d. Cylindricality, the preferred configuration dwelt upon principally herein, yields comfortably, where desired and appropriate, to other configurations, such as conicality, bowed-convex-/concavality, and so on.
In addition to, and separate from, the advantages offered (in certain invention modifications) by a rotary shaftless driving interconnection between an aerodynamic rotor and a generator rotor, one further important contribution of certain other implementations of the system and methodology of the present invention is the direct linking of a hoop-type aerodynamic rotor with the rotor in an electrical generator, regardless of whether or not any intervening rotary drive shaft is used. The direct-drive combination of such a hoop-type rotor and generator rotor, even in the presence of an intercoupling rotary shaft, has been found (in some instances) to be desirable, and an advance over prior art approaches.
Still another important object of the invention, in certain ones of its proposed configurations, is to employ a fixed (anchored), stationary shaft, and on that shaft, a support bearing structure (journal mechanism) for an aerodynamic rotor, which configuration minimizes to the point of substantially eliminating the fluctuating bending moments that always inescapably occur when a rotating shaft is used.
A further object is to provide a wind-turbine design that adapts to fluctuating wind velocity, and that minimizes the risk of failure at exceptionally high incident wind speeds.
In the context of pointing out various features and objects of the most preferred embodiment of the present invention, perhaps an important way of summarizing and characterizing an underpinning and key feature of this invention, which feature results in its offering substantial improvements over related, prior art, power-conversion systems and methods, and expressing this feature with reference to that which (above) has been characterized as the most preferred embodiment of the invention, is to focus on the fact that that applicant""s system and related methodology preferentially employ(s) direct, rotary shaffless coupling between a rotary, hoop-type air-foil and the rotor in an electrical generator. During operation of this system, these two rotors, along with the just-mentioned rotary shaftless coupling structure, rotate along with one another within a path, region or zone which is referred to herein as being described by, or as describing, a generally cylindrical locus.
On a somewhat broader plane, and talking now briefly here about a way of viewing the energy- and power-handling characteristics of this invention, and, further, doing this in the setting of one of its primary, current fields of applicationxe2x80x94the field of converting wind-power into electrical powerxe2x80x94the invention employs an aerodynamic rotor which effectively: (a) xe2x80x9ccollectsxe2x80x9d, on the kinetic-power side of the system, fluid-derivable (fluid-flow) power that exists in a given cross-sectional area of a flow of incident wind; and (b) extracts such energy/power from this flow at the perimeter of a rotating structure. This rotor then directly conveys captured and extracted power, in the form of mechanical rotation (or rotary mechanical power), and in a hollow, perimetral, rim-to-rim, rotating annular fashion (or connection), into the periphery of a rotor in an electrical generator. The electrical generator, on the electrical-power side of the system, converts such rotary power to electrical power.
This power-handling and conversion protocol, so-to-speak, accurately depicts two of the three, principal, general realizations of the invention described herein.
In the third general realization of the invention, a realization wherein a rotary power-transmission shaft is used as a xe2x80x9cconveyingxe2x80x9d mechanism, energy capture and extraction is, nevertheless, and according to the present invention, performed in substantially exactly the same xe2x80x9crotating annular regionxe2x80x9d manner.
In those system embodiments of the present invention which avoid the use of an intermediary rotating shaft as a mechanism for effecting power transfer to an electrical generator, such avoidance: not only (a) simplifies and makes less costly the construction of applicant""s system, when such is compared to the normal complexity and cost-of-manufacture associated with prior art systems; but also (b) removes from the xe2x80x9cpower-transfer environmentxe2x80x9d conventional, intermediate structure which would, were it present, introduce energy-losing, fatigue-inducing, cyclical bending moments and torques during the process of power transfer. Such commonly experienced cyclic loading extracts a certain amount of available energy which could otherwise be transferred, and it also diminishes the useful operational life of the rotating mechanical components of a system. The elimination of such prior art power-transfer structure, therefore, leads to a significant improvement in the efficiency of energy transfer between the environment of fluid-flow-power and the environment of electrical power. It also promotes increased, useful life of a system.
Important advantages and efficiencies, as mentioned earlier herein, have also been noted in another form of the invention, wherein a hoop-type aerodynamic rotor to couples power directly into the rotor in an electrical generator, regardless of whether or not such coupling takes place through a rotary shaft.
By connecting what can be thought of as the electrical output side of such an electrical generator to the input side of an appropriate power-electronic control structure, that control structure (which is offered as a component of the present invention) can be operated easily and effectively (at its output side) to eliminate telegraphing to the electrical (grid) side of the system fluctuations which would otherwise be introduced (by virtue of the fact that fluid-flow power, such as wind power, may be widely variable over time).
An additional and important benefit of eliminating (in one general approach offered by the invention) a power-transfer environment which includes a rotating shaft, is that the structure (which may be stationary, and elongate-shaft-like, in nature) that supports the rotating components of applicant""s system is not subjected to ever rotationally-changing, fatiguing, variable bending moments.
In the most preferred system implementation of the present invention, referred to hereinalso as a cup-shaped apparatus, the structure therein which rotates (as, for example, under the influence of impinging wind) can be thought of as including (on the aerodynamic side of the system) a rotary, elongate, cup-wall structure. This cup-wall structure includes: (a) a generally open-ended air-foil-rotor-wall-portion at the system""s wind-receiving front end; and (b) an electrical-generator-rotor-wall-portion, which forms part of the generator employed in the system. The generator""s stator is located operationally adjacent the generator-rotor-wall-portion (either within, next to, or circumsurrounding the mentioned generator-rotor-wall-portion), and is also talked about herein as being an end-wall, electrical-generator stator structure. The rotational components of the system rotate on and about a common longitudinal rotational axis, which axis nominally substantially parallels the plane of the underlying ground where the structural rendition of the invention is installed for use.
In such a system, the non-wind-receiving end of the rotary portion of the system is effectively normally closed to the through-flow of air. The xe2x80x9cclosurexe2x80x9d structure preferably includes what is referred to herein as a change-configuration, infinitely adjustable, back door structurexe2x80x94also referred to herein as a wind-barrier structure, and as a back door assembly. This part of the system includes change-position door structure that has selectively openable and closeable openings in the form of openable and closeable doors, or door expanses. The openness and/or closedness of these openings is adjusted, typically, directly under the influence of impinging wind activity, and is used to promote an operational behavior which allows the system to capture, and to use, as much wind-derivable power as possible, while at the same time dealing effectively with possible damaging wind overload conditions. In particular, this back door structure, under circumstances of overly high-velocity winds, opens appropriately to allow a certain amount of impinging wind effectively to escape the system without damagingly loading it. Various specific kinds of back door arrangements are described and illustrated herein.
One very interesting and promising modification of the present invention is one which includes a fluid-flow rotor, wherein positionally adjustable fluid-flow foils (the aerodynamic foils in an air-flow system) are disposed effectively in attack-angle xe2x80x9cplanesxe2x80x9d that are disposed at oblique angles relative to the rotor""s axis of rotation. Such foils can be employed both to capture fluid-flow power in order to impart rotation to the associated rotor, and as well, simultaneously, to act as a kind of back-panel, or back-door, arrangement. Selective (and preferably infinitely changeable) attitude adjustments made in these foilsxe2x80x94made either automatically in response to sensed changes in incident fluid-flow activity, or xe2x80x9cmanuallyxe2x80x9d in response to the intentions of an operatorxe2x80x94can change simultaneously how the rotor extracts (or bypasses) incident fluid-flow power.
A xe2x80x9cclose cousinxe2x80x9d to this kind of embodiment is one wherein foil-positioning adjustability is omitted.
These just-mentioned two modified forms of the invention are ones which lend themselves particularly well to the employment of a fluid-flow rotor which has the previously mentioned configurational xe2x80x9caspectsxe2x80x9d of conicality, bowed-convex-/concavality, etc.
A further very important concept to note as one now proceeds (as a student of the relevant art) investigatively into the descriptive material which shortly follows, is that the present invention weaves a potent strand of striking and fresh elegance into the developing structural fabric of fluid-flow-to-electrical power conversion. It does so by introducing, in the technical equivalent of a single artistic stroke, the ability to support (according to several important modifications of the invention) all required rotating elements, without the presence of a rotating shaft, via a direct support connection which is completely to one axial, xe2x80x9coutboardxe2x80x9d side of the whole combinational assembly of those elements. Combining additionally (with this significant configurational advance) employment in the whole combination of a relatively, axially, very thin electrical generator, as is described below, such combining anchors, for all skilled in the art, an immediate recognition of the engineering simplicity and sensibility of eliminating (under many if not most circumstances) a rotating connective shaft, and further of reducing, to an extraordinary level of structural minimization, the componentry required to support the rotating xe2x80x9cfluid-flowxe2x80x9d portions of a system above the ground. In certain instances, the various electrical circuit components which make up a control interface circuit, like the kind generally identified above, can be built directly into the structure of the generator. This constructional opportunity further enhances system compactness.
Other important objects and advantages that are offered by the present invention will become apparent as the description which now follows is read in conjunction with the accompanying drawings.